Cingular Treo 600 with Earthlink isp

With my Treo 180 I had AT&T Wireless for voice & I was able to connect through my dial-up Earthlink account & use voice minutes to get online. My Cingular Treo 600 has this feature locked out so I would have to buy their expensive plan (not interested).

Do I understand correctly that I can replace the Cingular firmware on my phone with the "unlocked" Palm One firmware? I assume this would let me enter my Earthlink dial-up account for internet access?

Are there any drawbacks to doing this? Warranty I assume would get voided if I sent it back like that, I would have to reinstall the Cingular firmware? Dial-up is slower & uses minutes; this is fine for my usage. Would the Cingular SMS still work with the Palm One "unlocked" firmware?

Mine doesn't seem to give me the option (mine being a t-mobile) and it stinks if you can't b/c i'd rather just use the minutes. All I want to do is check my yahoo mail and using the minutes doesn't bother me since I've got 3000 a month anytime. I had a treo 270 TMo version and it allowed me to do so. I also used dial up on a Motorola MPX200 MS smartphone. Sad thing was though the Moto was newer, the older 270 with a puny dragonball processor was much faster.

I bought a firmware on ebay, it was just a couple dollars. I was just having a tough time googling it & getting information. It is supposed to let me use any SIM card, I'll let you know if it helps with the dial up too.

In order to use the "Wireless Dial-up" under the network preferences settings, you'll need to call Cingular and have them add "Data Access CSD" also called "Wireless Internet" to your plan as a $4/month feature. T-Mobile automatically gives this to all of their customers but on Cingular it's a separate feature.
Search the forums for "CSD" you'll see a lot of discussion on this. Here are two specifica threads to get you started. But I do recommend searching on "CSD" to get even more.http://discussion.treocentral.com/sh...ad.php?t=99100http://discussion.treocentral.com/sh...ad.php?t=97776

Update: I bought my treo 600 unlock firmware for $5 from ebay user dbren23. It did unlock the SIM as stated in the auction. It did not unlock the Wireless Dial-up, he did not claim it would, I just thought I would give it a try.

The wireless dialup feature shouldn't be locked. You should be able to create a new network profile and chose "wireless dial-up" as the preferred connection type. As for the default Cingular network profiles, those are locked by Palm so you can't screw them up. Just create a new network profile.

I did "Create new". It tries to connect & then cancels out. I'll check with Earthlink to make sure it's not the isps fault or a problem with my account. The unlock-firmware I bought did not remove the Cingular logo & the firmware is still listed "...-CNG", the firmware I bought just unlocked the SIM with a code. I guess I need to get ahold of the firmware that ships with the Treos from Palm without a cell plan attached to it. Then it will truly be unlocked.

I just got off the phone with Cingular. They informed me that they stopped offering "Data Access CSD." They also confirmed that the phone is locked out of using wireless dial-up from other providers. So now I'm back to looking for the Unlocked Treo 600 Palm firmware.